Manufacture of benzanthrone



Patented Oct. 17, 1933 MANUFACTURE or BENZANTHRONE Alphons 0. Jaeger,Mount Lebanon, and Lloyd G. Daniels, Grafton, Pa., assignors' to TheSeldom Company, Pittsburgh, Pa., a corporation of Delaware No Drawing.Application July 24, 1929 7 Serial No. 380,751

8 Claims. (01. 260-61) This invention relates to the manufacture ofbenzanthrone.

In the past benzanthrone has been prepared from relatively pureanthraquinones produced by the chemical oxidation of anthracene orbysynthetic process from phthalic anhydride and benzol. It has also beenproposed to use highly purified anthraquinone produced by the catalyticoxidation of anthracene. Y

Surprising as it may seem we have found that anthraquinone of widevariation of purity as produced by the catalytic oxidation of anthraceneof extremely wide variation in anthracene content can be directly usedfor the production of benzanthrone, or in some cases can be used afterminor purification. The impurities present are very different than thoseusually encountered in the anthraquinone from chemical oxidation or fromthe condensation of phthalic anhydride and benzol. Thus, for example,certain oxidation products of phenanthrene, such as phenanthraquinone,diphenic acid, phthalic anhydride and maleic acid are present and inmany cases some oily impurities, e. g. dead oils, which, however, areevidently destroyed in the preparation of benzanthrone or are renderedharmless, and even in cases of very impure anthraquinone containing insome extreme cases up to 40% of impurities a very satisfactory grade ofbenzanthrone can be obtained. As the new methods of catalyticallyoxidizing anthracene of various grades of purity,

particularly the use of stabilized catalysts as described in theco-pending application of A. O. Jaeger, Serial No. 264,571 filed March24, 1928, can handle very low grades of anthracene which are extremelycheap, the present process opens up an important field for theproduction of benzanthrone from cheap materials, the use of which forsuch purposes has hitherto not been considered.

The present invention is not limited to the use of any particular gradeof impure anthraquinone and higher grades of, impure anthraquinoneproduced by catalytic oxidation of anthracene are included in theinvention. It should also be understood that derivatives ofanthraquinone, such as halogen-substituted anthraquinones, insofar asthese derivatives can be produced by catalytic oxidation, may be usedfor the production of the corresponding benzanthrones. Most of theimpurities in the crude anthraquinone which are not destroyed bysulfuric acid in the benzanthrone process are solids, and although thebenzanthrone reaction is heterogeneous as to phase, apparently theincrease in the amount of the solid phase due to the impurities does notin no sense limited to any theory as to the action of the impurities.

It is a further advantage of the present invention that theimpuritiesvvhich are not removed in the production of benzanthrone, andwhich may amount to as much as 40%, not only do not injuriously affectthe quality of the benzanthrone for caustic fusion to dib'enzanthrone,but actually act as reducing agents, permitting the elimination or areduction in the amount of added reducing agent required in theseprocesses. therefore, not only permits the production of benzanthronesfrom cheaper raw materials but the benzanthrones thus produced can bemore economically used in caustic fusions than can benzanthronesproduced from commercially pure Example 1 A sufficient amount of crudeanthraquinone containing to anthraquinone content, which may for examplebe obtained by the catalytic oxidation of 20 to 30% crude anthracene bymeans of a stabilized catalyst, is dissolved in 200 to 250 parts of 93to 95% sulfuric acid, the amount being such that the solution contains10 parts of 100% anthraquinone. The amount of acid used will varysomewhat, the larger amount of acid being used with the less pureanthraquinone, Preferably the anthraquinone is added slowly. at amoderate temperature (below 40 C.) with vigorous agitation to preventforming tarry lumps. After solution is complete, small portions ofaluminum in the form of powder, fine shot or turnings are added during45 to 120 The amount of metal added is 50% more than The invention,

that required to reduce the anthraquinone to oxyanthranol. Largeramounts of metal may be used, up to slightly more than necessary toreduce all the anthraquinone to anthranol, but the best yields areobtained when the amount of metal added is sufiicient to form a mixtureof anthranol and oxyanthranol, containing the latter in excess.

The mixture is then cooled to 10 C. or lower,

and sufiicient ice is added to dilute the acid to 86-88%, based on theoriginal amount of acid used and disregarding any formation of waterduring the reduction. The ice is added 'in small portions, preferablywith external cooling, which should be continued until more than half ofthe ice has been added so as to prevent the batch temperature fromrising above30 C. before the acid is below 90% concentration. 18 partsof glycerin, mixed with suflicient water to reduce the acidconcentration to -82% is run into the batch without cooling, and themixture is then heated to about 110 to 115 C., a vigorous reactionstarting and carrying the temperature up to 125 to 135 C. When thereaction moderates; outside heat is applied and the temperature ismaintained at 130 to 135 C. for two hours or longer, whereupon the batchis slowly dropped or blown into a 'lead-linedvat containing sufficientwater to dilute the sulfuric acid to a" concentration suitable forfiltering, for example 8 to 15%. More rapid filtering is obtained if 40to 50% of the water is present in the vat and is hot or actuallyboiling,'providing for a preliminary dilution, which is then followed byadding enough cold water to complete the dilution.

The precipitate is filtered off, washed acidfree with hot water and thenalternately with hot sodium carbonate solution, 0.1 to'0.2%concentration, and hot-water until the alkali removes no more coloredimpurities. The product is then Washed alkali-free with hot water anddried. An analysis shows 58 to 67% benzanthrone with a yield of -90% oftheory, and the crude product can either be directly used for fusionwith caustic alkalies for the preparation of dibenzanthrone, theimpurities serving in part as a reducing agent so that the amount ofreducing agent required is less than when high-grade benzanthrone isused, or, if desired, the crude product can be purified by extractionwith solvents or by sublimation processes where a purer benzanthrone isrequired for further operations.

Instead of using aluminum, copper powder or powdered metals moreelectropositive than copper may be used; alloys of high copper contentare also suitable. When copper is used, about three times as much copperis necessary as when aluminum is used, and the reduction is preferablycarried out at 15 to 20 C. higher temperature.

Example 2 Crude anthraquinone of 75to90% purity, which may be obtainedby the catalytic oxidation of crude anthracene of 30 to 50% purity withstabilized catalysts under especially controlled conditions, issubjected to the same treatment as described in Example 1. Crudebenzanthrone of 68 to 80% purity is obtained which is well adapted forcaustic fusions and which can be easily purified by extraction andcrystallization from solvents or by sublimation, particularly when thesublimate is condensed at predetermined temperatures.

Example 3 An anthraquinone of to purity, obtained by the causticoxidation of semi-refined anthracene of 60 to 10% content, is subjectedto the treatment described in Example Land results in a crudebenzanthrone of 7 8 to 88% purity.

Instead of using a process as described in Example 1, the followingprocess may be used. An amount of anthraquinone corresponding to partsof 100% anthraquinone is dissolved in 1500 to 1800 parts of 95% sulfuricacid. The mixture is cooled with vigorous agitation to 10 C. or lower,and ice is added with continued cooling to reduce the concentration ofthe acid to 85 to 87%, requiringabout 225 to 290 parts of ice. Thetemperature ofthe mixture is permitted to rise to 40 to 50 C. at thefinish of this preliminary dilution. A mixture of 200 to 250 parts ofglycerin, '97 to 98 parts of aniline oil and sufficient water to dilutethe acid to 82% concentration is run slowly into the batch. Incalculating the amount of water required, the amount of acid neutralizedin the aniline should be taken into consideration, or, if desired,aniline sulfate may be used. During this addition, the temperature ofthe batch is permitted to rise, butshould not be allowed to exceed 90 C.After all of the glycerin and aniline have beenadded, the batch isheated until a vigorous reaction starts, when the heat of reaction willtake the temperature up from about 115 to 130 C. Cooling should be used,if necessary, to keep the temperature at 130 to 135 C. for 30 to 60minutes. In some cases some outside heat will be necessary.

The product is isolated as described in Example 1 and is about 2 to 3%vlower purity than the product prepared by using the metal. The yield,however, is slightly better, 2 to 4%, and the prod- ,uct can be useddirectly for caustic'fusions to dibenzanthrone.

The derivatives ofanthraquinone, such as halogen-substitutedanthraquinones, may be used in this process, producing the correspondingbenzanthrones.

Example 4 Off-grade products from the sublimation of catalyticanthraquinone and which contain impurity than when commercially pureanthraquinone is used.

Example 5 dissolving the anthraquinone in the concentrated intermediateheat treatment is applied, the final crude benzanthrone is considerablypurer due to the more complete removal of the impurities as with causticalkalies in the presence of a reducing agent.

2. A method of producing caustic alkali fusion products of benzanthronesubstances, which comprises subjecting an impure anthraquinone from thecatalytic oxidation of anthracene to condensation with glycerol to forma benzanthrone substance and subjecting the product without removal ofalkali-insoluble impurities to fusion with caustic alkalies in thepresence of an amount of reducing agent less than that required for thefusion of pure benzanthrone under the same con ditions. V i

3. A method according to claim 2, in which 'the anthraquinone isproduced by the catalytic oxidation of crude anthracene.

4. Amethod according to claim 2, in which the anthraquinone is a tailingfrom the condensation of vapors from the catalytic oxidation ofanthracene.'

5. A methodaccording to claim 2, in which the anthraquinone is atailingfrom the condensation of vapors from the catalytic oxidation 'ofanthracene, at least a part of the condenser having been maintained at atemperature at which pure anthraquinone precipitates out and the impuri-.ties remain volatile.

6. A method according to claim 2, in which the impure anthraquinone isreduced not materially beyond the anthranol stage before condensationwith the glycerin. V

'7. A method according to claim 2, in which the anthraquinone is reducedto a mixture of anthranol and oxyanthranol before condensation withglycerin. I e

8. A method according to claim 2, in which the impure anthraquinone isreduced in a sulfuric acid solution and the reducedproductwithoutisolation caused to react with a substance in;

cluded in the group consisting of glycerin, acrolein and othersubstances which are transformed into acroleinwhen heated with sulfuricacid.

. ALIF'HONS O. JAEGER.

LLOYD C. DANIELS.

